1. Field of the Invention
This invention relates to an improved fluid seal between a reciprocating piston sliding in a cylindrical bore, wherein a significant pressure differential, on the order of at least three thousand pounds per square inch exists across the opposite ends of the piston. Such fluid seals are required, for example, to journal the reciprocating piston elements of a high pressure reciprocating pump.
2. Description of the Prior Art
Reciprocating pumps have been commonly employed in the oil processing industry to develop fluid pressures in excess of three thousand pounds per square inch. In many oil field pumping applications, the fluid comprises a mixture of oil with water and other low viscosity fluids so that the viscosity of the mixed fluid to be pumped is significantly less than that of oil. The reciprocating pumps heretofore employed for such applications have utilized a piston element of relatively small diameter moving in a cylindrical chamber. Because of the relatively high viscosity of the oil, it has been common heretofore to employ smooth, precisely finished cylindrical surfaces on both the piston and the piston chamber to achieve a very limited mechanical clearance between such surfaces to effectively reduce any leakage of the fluid by providing only a limited clearance laminar flow path for the pressured fluid. While such configurations were satisfactory for relatively low pressure pumps and high viscosity fluids, the technical demands of modern oil processing equipment require higher pressures to be developed, and mixed fluids of significantly lower viscosity, and even water alone, to be handled by the pressure generating pump. This has resulted in increased leakage of the fluid through the laminar flow seals normally provided around the pistons of high pressure pumps to a degree as to significantly reduce the efficiencies of such pumps in modern oil processing applications.